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kernel/linux-imx6_3.14.28/drivers/scsi/arm/msgqueue.c 3.79 KB
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  /*
   *  linux/drivers/acorn/scsi/msgqueue.c
   *
   *  Copyright (C) 1997-1998 Russell King
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   *  message queue handling
   */
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/stddef.h>
  #include <linux/init.h>
  
  #include "msgqueue.h"
  
  /*
   * Function: struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq)
   * Purpose : Allocate a message queue entry
   * Params  : msgq - message queue to claim entry for
   * Returns : message queue entry or NULL.
   */
  static struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq)
  {
  	struct msgqueue_entry *mq;
  
  	if ((mq = msgq->free) != NULL)
  		msgq->free = mq->next;
  
  	return mq;
  }
  
  /*
   * Function: void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq)
   * Purpose : free a message queue entry
   * Params  : msgq - message queue to free entry from
   *	     mq   - message queue entry to free
   */
  static void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq)
  {
  	if (mq) {
  		mq->next = msgq->free;
  		msgq->free = mq;
  	}
  }
  
  /*
   * Function: void msgqueue_initialise(MsgQueue_t *msgq)
   * Purpose : initialise a message queue
   * Params  : msgq - queue to initialise
   */
  void msgqueue_initialise(MsgQueue_t *msgq)
  {
  	int i;
  
  	msgq->qe = NULL;
  	msgq->free = &msgq->entries[0];
  
  	for (i = 0; i < NR_MESSAGES; i++)
  		msgq->entries[i].next = &msgq->entries[i + 1];
  
  	msgq->entries[NR_MESSAGES - 1].next = NULL;
  }
  
  
  /*
   * Function: void msgqueue_free(MsgQueue_t *msgq)
   * Purpose : free a queue
   * Params  : msgq - queue to free
   */
  void msgqueue_free(MsgQueue_t *msgq)
  {
  }
  
  /*
   * Function: int msgqueue_msglength(MsgQueue_t *msgq)
   * Purpose : calculate the total length of all messages on the message queue
   * Params  : msgq - queue to examine
   * Returns : number of bytes of messages in queue
   */
  int msgqueue_msglength(MsgQueue_t *msgq)
  {
  	struct msgqueue_entry *mq = msgq->qe;
  	int length = 0;
  
  	for (mq = msgq->qe; mq; mq = mq->next)
  		length += mq->msg.length;
  
  	return length;
  }
  
  /*
   * Function: struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
   * Purpose : return a message
   * Params  : msgq   - queue to obtain message from
   *	   : msgno  - message number
   * Returns : pointer to message string, or NULL
   */
  struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
  {
  	struct msgqueue_entry *mq;
  
  	for (mq = msgq->qe; mq && msgno; mq = mq->next, msgno--);
  
  	return mq ? &mq->msg : NULL;
  }
  
  /*
   * Function: int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
   * Purpose : add a message onto a message queue
   * Params  : msgq   - queue to add message on
   *	     length - length of message
   *	     ...    - message bytes
   * Returns : != 0 if successful
   */
  int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
  {
  	struct msgqueue_entry *mq = mqe_alloc(msgq);
  	va_list ap;
  
  	if (mq) {
  		struct msgqueue_entry **mqp;
  		int i;
  
  		va_start(ap, length);
  		for (i = 0; i < length; i++)
  			mq->msg.msg[i] = va_arg(ap, unsigned int);
  		va_end(ap);
  
  		mq->msg.length = length;
  		mq->msg.fifo = 0;
  		mq->next = NULL;
  
  		mqp = &msgq->qe;
  		while (*mqp)
  			mqp = &(*mqp)->next;
  
  		*mqp = mq;
  	}
  
  	return mq != NULL;
  }
  
  /*
   * Function: void msgqueue_flush(MsgQueue_t *msgq)
   * Purpose : flush all messages from message queue
   * Params  : msgq - queue to flush
   */
  void msgqueue_flush(MsgQueue_t *msgq)
  {
  	struct msgqueue_entry *mq, *mqnext;
  
  	for (mq = msgq->qe; mq; mq = mqnext) {
  		mqnext = mq->next;
  		mqe_free(msgq, mq);
  	}
  	msgq->qe = NULL;
  }
  
  EXPORT_SYMBOL(msgqueue_initialise);
  EXPORT_SYMBOL(msgqueue_free);
  EXPORT_SYMBOL(msgqueue_msglength);
  EXPORT_SYMBOL(msgqueue_getmsg);
  EXPORT_SYMBOL(msgqueue_addmsg);
  EXPORT_SYMBOL(msgqueue_flush);
  
  MODULE_AUTHOR("Russell King");
  MODULE_DESCRIPTION("SCSI message queue handling");
  MODULE_LICENSE("GPL");